In various dental surgical procedures, jaw surgery in general and work with oral implants, it is a common practice to insert a cylindrical implant into a bore or implant cavity provided for this purpose in the jawbone of a patient.
A number of problems have been encountered in connection with the drilling of such cavities and indeed, these problems can be so severe that in some cases the use of implant techniques must be discarded since there are no anatomical conditions in which a satisfactory attachment of the implant can be guaranteed. Such cases include, for example, the lack of sufficient bone substance for an implant cavity.
However, even when there is sufficient bone substance for an implant cavity, problems have been encountered in the past in forming the implant cavity with a sufficient degree of precision and parallelity, especially where a number of implant cavities are required in a certain region of a jawbone.
Usually such bores are formed in a freehand manner in the jawbones. Of course, this can readily result in defective bores. An especially great danger is the drilling of the bore to an excessive depth so that the Sinus Maxillaris or the Canalis Mandibularis is trepanned.
Of course, there is also a danger that the bore will be at such an inclination that the spongiosa will be excessively damaged in the transverse direction. Such damage can result in jaw resorption. The importance of the transverse dimension is that with implantation, one should ensure a thickness of about 1 mm of spongiosa between an implant and the laminar externa and interna of the respective jaw structure to ensure a sufficient blood supply around the implant and hence growth of bone tissue around the implant to anchor it.
Failure to maintain precision with respect to this dimension has been found to be the cause of a variety of problems.
It has been found that especially later, when the implant is subjected to loading and when the implants are not exactly parallel to one another or to the teeth, that there is a vertico transverse pressure transmission to the implant.
This vertico transverse loading provides a pressure effect on one side of the implant and a tension effect on the opposite side.
Both effects increase, over extended periods, the bone resorption effect and give rise to a funnel-shaped bone resorption pattern which can produce secondary infections around the implant.